The present invention relates to a process for the preparation of N-arylarylsulfonamide compounds by the reaction of a chlorosulfonylaryl compound with an arylamine compound.
N-Arylarylsulfonamide compounds, which are important as agricultural and pharmaceutical chemicals, are often difficult to prepare by condensation of the corresponding chlorosulfonylaryl and arylamine compounds. This is particularly the case for the preparation of N-arylarylsulfonamide compounds derived from deactivated arylamine compounds; that is, from arylamine compounds possessing bulky substituents located on a carbon atom adjacent to the amino nitrogen group (ortho substituents) and/or electron attracting substituents. It is also especially the case for the preparation of N-arylarylsulfonamide compounds derived from chlorosulfonylheteroaromatic compounds. The problem has been reported, for example, in the preparation of certain herbicidal N-(substituted phenyl)1,2,4!triazolo1,5-c!pyrimidine-2-sulfonamide compounds and related triazolopyrimidinesulfonamide compounds (U.S. Pat. No. 5,163,995). It has been disclosed that some such condensation reactions can be improved by the addition of a molar amount or more of a pyridine base (U.S. Pat. No. 4,818,273), or by the addition of a catalytic combination of pyridine and dimethylsulfoxide (U.S. Pat. Nos. 5,163,995 and 5,177,206). Further, it has been disclosed that such condensation reactions can be improved by first converting the arylamine compound to an N-trialkylsilylarylamine derivative (U.S. Pat. No. 4,910,306). The problem of slow reaction rates and poor yields persists, however, and improved methods of condensing chlorosulfonylaryl compounds with poorly reactive arylamine compounds that produce the desired N-arylarylsulfonamide compounds rapidly and in good yield would be of considerable value.
The condensation of 2-chlorosulfonylthiophene with aniline and some meta and para substituted anilines was disclosed by A. Arcoria et al. in Journal of Heterocyclic Chemistry, 12, 333-335 (1975) and in Tetrahedron, 33, 105-111 (1977) to be faster in certain simple alcohol solvents than in certain dipolar aprotic solvents. No yield information was given.